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1. INTRODUCTION
Osseointegration in clinical dentistry depends on an understanding of
the healing & reparative capacities of hard and soft tissues. Its objective is a
predictable tissue response to the placement of tooth root analogues. Such a
response must be a highly differentiated one, and one that becomes
organized according to functional demands.
The word osseointegration consists of “OS” the Latin word for bone
and “Integration” derived from the Latin words meaning the state of being
combine into a complete whole.
In 1952, Dr. Per – Ingvar Branemark, M.D., Ph.D. had studied the
concept of tissue integrated prostheses at the Laboratory of Vital Microscopy
at the University of Lund, and subsequently at the Laboratory for Experimental
Biology at the University of Goteborg.15 The basic aim has been to define
limits for clinical implantation procedures that will allow bone and marrow
tissues to heal fully and remain as such, rather than heal as a low
differentiated scar tissue with unpredictable sequelae. The studies involved
analyses on tissue injury and repair in diverse sites in different animals, with
particular reference to micro vascular structure and function. Special
emphasis was placed on analyzing the disturbances caused in the
intravascular rheology of blood by means of series of different methodological
approaches.
1

2. The notion of permanently anchoring a prosthesis in bone through the
skin or mucosa has fascinated clinical researchers over the years. The
anticipated (and encountered) biomechanical difficulties have been formidable
ones, since the clinical remit is to almost simultaneously control atleast four
factors.63
1. The selection of an acceptable biocompatible material and a correct
implant design.
2. The preparation of a host bone site, which ensures a predictably
favorable healing response, one that can cope with subsequent stress
loading.
3. The design and fabrication of a prosthesis that does not undermine that
integrity of the acquired bony attachment.
4. The provision of a sealing mechanism at the implant skin or implant –
mucosal junction.
2

3. ENDOSSEOUS OSSEOINTEGRATED DENTAL IMPLANT
3

4. REVIEW OF LITERATURE
Reishick MH, Benson D72 reported a study to evaluate the response
of monkey tissue to coatings of porous alumina that were applied to chromecobalt subperiosteal denture implants. Initial results showed evidence to
indicate that a direct attachment occurs to the alumina surface i.e. the tissue
surrounding the removed alumina implant was tenaciously attached.
Reisbick MH, Benson D and Furstman LL72 reported that permanent
fixation of subperiosteal implants occurs by dense, collagenase fibrous tissue
encapsulation around the frame work. An epithelial cuff may form around the
implants, similar to that occurs around the natural tooth. Porosity in ceramic
materials has been found to allow in growth of soft tissues. The impervious
ceramics implanted in soft tissues were found to be encased by the tissues.
The pilot study did by the authors investigated the effect of aluminacoated subperiosteal implants indicates a direct attachment occurs to the
alumina surface, while a chrome-cobalt implant was retrieved readily with no
tissue adherence. The histologic findings indicate that bond formed at the
junction of the tissue attachment to the implant is the prevention of downward
growth of oral epithelium.
4

5. Richards LW, Gourley IM, cordy DR73 conducted a pilot study to
obtain basic data regarding tissue response to the implants, and to study the
problems of mobility and possible infection. The results of the study showed
that Ti endosteal implants, were passively accepted. There was no
inflammatory response to the implants and osteoclastic activity about the
blades was normal. There is no abnormal epithelial migration about the struts.
Epithelium was different to the metal near the neck of the implants. A dense
connective tissue generally surrounded the implants, especially thick near the
gingival surface.
Shpiro P, Binderman I81 reported that increased distribution of
stresses on bone is obtained with the blade-type endosteal implants in
comparison with the root form implants and it was demonstrated on the basis
of mathematical evaluation.
Pressure is defined as force acting per unit area. Greater the surface
area of contact with the bone, the pressure directed by implant on bone is
less. The amount of resulting pressure differs from shape of implants and
bone-to-implant contact area.
A mathematical evaluation of the shape of implants indicates that with
the force (F) of the distance from the centre of rotation to point of force
application (L) being equal and with equal surface areas (S). The resulting
pressure will be less in an implant with a larger mean distance of the support
5

6. from the centre of rotation. So, blade type implants results in less pressure on
bone as compared to the root resembling forms.
Kydd WL, Oaly CH47 reported the nature of shear bond
strength that develops between alveolar bone and Ti hollow implants. The
implants were placed in edentulous region of the mandibles of dogs. They
were conical in shape with circumferential grooves, 5 months later implants
were rotated. The nature of response to torque Vs rotation indicates no actual
adhesion between the bones of the Ti surface, other than frictional interaction.
The contact pressure at the interface was produced by the action of the
bone growing into the grooves. The stresses developed by the growing bone
on contact pressure affect the pattern of bone laid resulting in cessation of
growth.
Roy L, Raymond J, Grenable DE14 reported a patient who had died
with a 12 year subperiosteal implant denture, was studied and results of the
examination of the mandible after the death revealed absence of significant
damage to the approximating and adjacent tissues histologically. Thus well
made subperiosteal implants CD may offer selected patients many year of
denture efficiency of comfort unobtainable by other methods.
Albrektsson T4,6,7 reported that the insertion of any given foreign
material in a bone site is a multifacet problem that involves the implant,
6

7. adjacent tissue of the interface between implant and tissue. The interfacial
behavior between implant and tissue is determined not only by the nature of
implants (its chemical composition, surface conditions and mechanical
properties) and the state of the tissue per se, but also by the technique of
loading the implant.
A connective tissue anchorage of dental implants is an indication of
failure. The achievement of a solid bone anchorage for a dental implant can
lead to predictable long-term clinical results. This appears to depend on the
control of the surgical trauma, the condition of tissue bed, implant loading
conditions of the biocompatibility of the material used. In this manner a
meticulous clinical approach can ensure a lasting and successful bone
integration of an extracorporeal substitute.
Kasemo B40 reported the most important boundary conditions, which
relates to the future success or failure of implant procedures provided by the
surface properties of the implant. The implants are prepared first by careful,
controlled mechanical shaping of pure titanium raw material. The air exposure
forms an oxide layer of 100A with in a millisecond and 50-1000A within a
minute. Then additional growth of oxide layer is formed by cleaning and
autoclaving. The chemical properties of the interface chemistry are
determined by the oxide layer and not by the metal itself. Ti implants are
regarded as oxide ceramics.
7

8. Two
types of
chemical bonds may be
established
between
biomolecules and implant surface, these are weak, long-range Vander Waals
bonding and strong, short-range covalent and ionic bonds. The contributing
factors to successful results which prove titanium as implant material may be
combination of the chemical inertness (of its oxide), and the high dielectric
constant of the oxide.
Eriksson AR, Albrektsson T32 reported a study using a thermal
chamber to investigate and analyze hard tissue changes after heating in the
range of 470 to 500C.
The results of this study showed that bone tissue is sensitive to heating
at the level of 470C, and even greater injury after heating to 53 0c for 1 min.
Heating to temperature of 600 or more resulted in a permanent cessation of
blood flow and a bone tissue necrosis which showed no signs of repair over
periods of 100 days or more.
Rams T, Keyes P71 reported a study to investigate the sub gingival
microbiologic flora associated with gingival tissue protruding implants using a
direct phase contrast microscopy.
The results showed a significantly higher levels of spirochetes and
accumulated crevicular PMN‟s found in sub gingival plaque of the failed
implants due to >10mm pocket formation on implants with 3-5mm pockets
8

9. showed higher proportions of nonmotile coccoid cells and lower levels of
spirochetes of crevicular leukocyte.
McKinney RV, Koth DL61 reported that endosseous dental implants
function in 2 separate environments, internal environment of bone and soft
tissue of the external environment of oral cavity. Based on word origin and
definition, the terms permucosa, perimucosal and transmucosal can all be
correctly used. A study of definitions suggests that the most descriptive term
is per-perimucosal seal, where permucosal designates the vertical orientation
of the implant penetration through the oral mucosa and perimucosa
designates the horizontal or circumferential seal of the mucosa to the
biomaterial.
Gould TRL, Westbury L36 reported a study to determine the behavior
of epithelium in vitro is similar to its attachment behavior in vivo by the use of
small sections of Ti –coated implants inserted in human gingiva.
On examination of thin sections showed epithelial cells attached to Ti in
a manner similar to that observed in vitro and similar to the way in vivo, with
the formation of hemidesmosomes of basal lamina. The ability of the oral
epithelium to form such an attachment with the implant is the crucial factor in
the determination of clinical success or failure.
9

10. Doundoulakis JH29 reported a study by measuring and comparing the
effects of 5 sterilization methods on the Ti surface of the implant.
The 5 sterilization methods are (1) endodontic glass bead sterilizer (2)
autoclave conventional (3) Dry heat (4) UV radiation (5) Radio-frequency glow
discharge treatment.
Results showed that sterilization of low surface energy materials by
radio frequency glow discharge treatment of may be recommended for
obtaining a high surface energy character that correlates with induced cell
adhesion of implant fixation.
Kay JF, Golec TS, Riley RL43 reported that subperiosteal dental
implant designs from inception share a basic design feature. The distribution
of forces over a large foundation region by connected struts. The simplified
strut designs used presently are modifications of former elaborate lattice
designs.
The design of prosthesis must allow load transfer from the denture to
the post and to the strut structure without stress concentration or to cause
metal failure by static / cyclic fatigue mechanism.
10

11. HA coatings applied to the struts of subperiosteal implants can
positively affect the implant, by creating a faster and stronger attachment to
the bone. And make metallic subperiosteal implant more biocompatible.
Lundgren D. Bergendal T53 reported a study to investigate the pattern
of occlusal forces in dentitions restored with osseointegrated implant
supporting FPD‟s in the lower jaw and CD in upper jaws.
The occlusal force pattern during chewing and biting showed chewing
pattern was comparable to that reported for subjects which complete healthy
dentitions or with tooth supported cross-arch FPD.
The posterior cantilever segment in the present FPD cantilever
prosthesis occluding which CD exhibited greater local forces when compared
to occluding with natural teeth.
Lindquist LW, Carlsson GE50 reported a study by analyzing bone
resorption around fixtures in association with treatment of the edentulous
mandible with fixed prosthesis of tissue-integrated implants, measured by
means of stereoscopic intra oral radiography.
The results of the study showed 0.5mm bone loss during first year and
thereafter 0.06-0.08mm annually for an observation period of 6 years. More
bone was lost around the most posterior ones.
11

12. Nikai H, Tsuru H78 reported a study to compare the structural
differences of bone-implant interface after nontapped and tapped insertions
for submerged endosseous implants using Tio2 coated and non-coated screw
type Ti-alloy.
Results showed that all implants by tapping insertion were healed with
direct bone apposition whereas implants by nontapping insertion revealed
some degrees of fibrous connective tissue intervention between bone and
implant.
No difference was found between Tio2 coated and non-coated
materials.
Koth DL, Steflick DE, Davis QB46 reported 5-year clinical results of a
single crystal aluminum oxide endosteal dental implant and evaluated the
clinical index parameters developed. Statistical analyses were performed on
the quantifiable clinical parameters.
On the basis of clinical observation and statistical analysis, the single
crystal sapphire endosteal dental implant met the clinical standards and
considered clinically acceptable. Statistically 77.7% of all implants placed and
95.5% of implants used as prostheses abutment were providing satisfactory
service 5 years after insertion.
Mentag PJ, Kosinski TF62 reported fabrication of a maxillary obturator
prosthesis using the intra mobile cylinder (IMZ) dental implant system.
12

13. The obturator prosthesis establishes oro-nasal separation and restores
missing teeth to increase chewing efficiency and an esthetic appearance and
further speech articulation of resonance.
The dental implant placement and the resultant increased stability of
retention on the prosthesis enhanced the overall function of psycho social
satisfaction of the patient.
Lum LB, Beirne OR, Curtis TA51 reported a study by directly
comparing the implant-bone interface of loaded and unloaded core-vent of
Biotes implants placed in the same group of non-human primate.
The results of this study showed that both core-vents of biotes implants
adhered according to the requirements described by Branemark to achieve
osseointegration when compared to the response of bone to the unloaded
and occlusally loaded on non human perimeter model at light microscopic
level after 5 months of occlusal loading.
Campagni WV, McGlumphy EA, Peterson LJ19 reported a study to
compare the difference in the stress patterns generated in photo elastic
plastic by an IMZ implant with a resilient or a rigid internal element. Under a
standardized cantilever load, the stress patterns were photographed in the
filed of a circular polariscope.
13

14. The static load conditions of the model demonstrated no statistical
difference between the area of stress pattern generated by an IMZ implant
with or without a resilient internal element.
Rieger MR, Kinzel GL, Brose MO76 reported a study to compare the
use of bioactive coatings on 3 endosseous implants by using finite element
analysis to determine whether bone-bonding or bone adaptation was
biomechanically more beneficial.
Results showed that although a bonded interface between an implant
of its host tissues may be biochemically beneficial bone bonding, may not be
biomechanically beneficial to the implant or the surrounding bone.
Tuminelli FJ88 reported a clinical report of a technique using free
vascularized bone grafts with the placement of Ti implants.
The successful application of micro vascular surgery, coupled with
grafting techniques of the osseointegrated Ti implants enables the author to
achieve improved reconstructive results for his patient who has experienced
reaction of the mandible due to cancer.
The
reports
showed
superior
rehabilitation
results,
enables
reconstructive team to restore functional esthetic levels, previously not
possible after radical surgery.
14

15. Richter EJ74 reported that common goal for all the implant systems are
to achieve a stable anchorage of implant body to bone tissue by contact
osteogenesis.
The implants with definite resilience integrated in the implant design
can diminish to vertical, horizontal electric stresses on bone to avoid bending
of the implant resulting form the elasticity of bone and to achieve a mobility
that is almost equal to that of the natural teeth.
Denissen HW, Kalk W, Hoof AVD27 reported an 11 year clinical
research study with both unloaded bulk HA implants and loaded HA – coated
Ti implants.
The results indicate that the design of bulk HA and time of implantation
should be changed because former causes degeneration and subsequent
permucosal exposure of implant occurred while latter causes difficulty in
closing the extraction wounds. Further cement fractures occasionally occurred
resulted in plasma spray coatings of HA on Ti cores.
Hence, this long-term research indicates that cylindrical HA implants
are reliable device as natural tooth substitutes that bond directly to bone
instead being simply osseointegrated.
15

16. Rieger MR, Brose MO, Adams WK75 reported a study to evaluate 3
endosseous post-type implant geometries: a serrated solid with 2 0 taper of a
rectangular cross section, a cylindrical screw type solid of a finned solid with a
109‟ taper circular cross section.
Examination of contour plots showed that increasing the material
stiffness transmitted more occlusal load to apical bone for all geometry. There
plots further suggests that an implanted material can be too stiff as the
punching stress increases at the apex and the implants elastic behavior is not
the only governing factor but the implants geometry seems to be the
determining factor in properly distributing stresses from implant to the bone.
Schewiger JW79 reported a study to determine whether Ti implants
can be safely placed and osseointegration achieved in irradiated bone of
beagle dogs.
The beagle dogs were irradiated previously allowed healing and Ti
implants place after 9 months and allowed to heal an additional 51/2 months
for osseointegration. The obtained block specimens showed that about half of
the specimens achieved osseointegration.
McCartney JW58 reported ear prosthesis retained with magnets by
attaching it to an implant – retained magnetic alloy.
16

17. The implants were placed in temporal bone to retain attachments for
ear prosthesis. A screw retained magnetic allow casting was used to retain an
acrylic resin magnet keeper to which silicone ear prosthesis was attached.
The keeper provided vertical support for the prostheses and facilitated
orientation for prosthesis insertion stability and retention was provided without
the use of adhesives.
Colley DR, Dellen AFV, Windeler AS et al24 reported that calcium
phosphate of hydroxyl apatite is example of CPC materials that bond directly
or chemically to bone. The ability to bond chemically to bone without a
mechanical inter lock is an important distinction between CPC and titanium
implants.
The author used a method by applying hydroxyl apatite to implant
surfaces and noted the thickness and physical properties of such coating
affecting the surface of implants. Histological analysis of bone implant
interface showed that coated implants had greater direct bone contact
compared with noncoated implants. The implant sputter coated from a
hydroxyapatite target will accentuate the healing of bone at the implant
interface by forming an amorphous layer of CPC coating. This coating
resulted in higher osseointegration rates and greater pull-out strengths.
17

18. Chavez H, Ortman LF22 reported that most of the implant literature
suggests that successful dental implants which are immobile of any detected
mobility indicate implant failure.
Clinically successful implants are not immobile, but have a range
mobility that is attributed primarily to the damping like character of the
bon/implant interface. The range of mobility with a PTV of -6 to +2. In addition
implants that support over dentures were significantly less mobile than
implants that support fixed prostheses.
Sagara M, Akagawa Y77 reported that the initial stages of bone healing
with Ti alloy implants were compared clinically and histologically of beagle
dogs for 3 groups namely
Group 1
-
Unloaded one-stage
Group 2
-
loaded one-stage
Group 3
-
unloaded two stage.
Significant crestal bone loss in group 2 showed poor bone apposition to
the bottom of the threads in the upper portion of the implant, but new bone
growth was seen in group 1 to group 3. These differences could be attributed
to the effect of early occlusal loading on the implant during initial bone
healing.
18

19. Akagawa Y, Tsuru H2 reported that the clinical and histological
evaluations of partially stabilized zirconia endosseous implants under
unloaded and early loaded conditions in 4 beagle dogs showed loss of crestal
bone height around loaded implants. The loaded new zirconia implants were
not encapsulated by fibrous connective tissue as shown by the approximately
70% of the bone contact ratio, and the implants were not mobile.
Lill
W,
Thornton
B48
reported
that
long-term
success
of
osseointegrated implants can be measured if the results of recover
examinations are systemically documented. The optimal method is the life
table analysis, which is a statistical method designed by Kaplan – mear and
cutler - ederer in 1958.
The author conducted the study to calculate the success potential of
683 implants (IMZ and Branemark). The results showed that loss of
Branemark implants during the healing period was greater than for IMZ
implants. IMZ implants were the most successful in partially edentulous
mandibular Branemark system was most successful in totally edentulous.
Artzi Z Tal H, Moses O, et al10 reported that success/ failure of implant
depend partially on the ability of the mucosa to form a seal around the implant
and the nature of the mucosa surrounding it.
19

20. Masticatory mucosa with stand stresses imposed on them much better
than the vestibular mucosa. Further it helps to maintain adequate oral
hygiene; the author discusses various mucogingival surgical techniques that
can be employed during surgical phase, during prosthetic phase and after
prosthetic phase. Lack of masticatory mucosa and presence of alveolar
mucosa are often associated with plaque, resulting in inflammation and
subsequent peri-implant destruction.
Yan J, Xiang W, Baolin L et al90 reported a study to establish a
method for combining bovine BMP with Ti and evaluated the early bone
formation induced by the bBMP/ Ti complex in edentulous dogs.
Result showed newly formed bone within the interface in two weeks
and complete osseointegration occurs in four weeks. Bone formed with the
apical opening of the implant within one month. So this study indicates that
osseointegration can be enhanced by bBMP bone induction. The apical
opening may provide a site in which osteogenesis can occur with protection
from implant stress before and after loading.
Charkaur HG, El waked MT21 reported a study on stress analysis
comparing the ISIS implant with a stress-eliminating space of a rigid stress
vent implant that are connected to the same abutment and also evaluated the
new TPS implant modification, which contained a resilient material on top of
the implant, with and without resilient material, with the same method.
20

21. The results showed that the resilient implant ISIS system showed less
stress than a rigid screw-vent implant when connected to a natural abutment.
The modified resilient implant head reduced stresses transferred to the
implant and its head distributed load between the implant and the abutment.
Nelson SK, Schuster GS66 conducted a study to evaluate the
influence of Ti Surface oxide composition and surface roughness on P.
gingivalis and E. Coli LPS affinity for CP1 and Grade -5 specimens. The
results of this study showed that different LPS molecular structures did not
influence LPS affinity for Cp 1 and Grade 5 Ti did not result in different LPS
affinity and surface roughness did not influence LPS affinity.
Bryant RS, Zarb GA18 conducted a study which aimed to test the
hypothesis that there is no difference between older and younger adults in
osseointegration.
Osseointegration involves an osseous healing response that may me
compromised by aging. The results of this study answers three points that
First, the age alone should not be used to exclude patients from being
given oral implants.
Second osseointegrated implants can be maintained as patient‟s age,
even in older patients as they become increasingly debilitated.
21

22. Finally, it lends itself diversity of prosthodontic application well in both
age groups.
Cooper LF26 reported that Osseointegration involves both the
formation and the maintenance of bone at implant surfaces, and to identify
cellular and molecular determinants of bone formation that may be used in
clinical attempts to enhance or expand the application of endosseous implants
for dental and craniofacial prosthetics.
Osseointegration depends on the activity of osteoblastic cells to form
bone and the lifelong maintenance of this bony support. Although changes in
implant design, surgical technique, and restorative method may be improved
with regard to osseous responses, the fundamental aspects of bone cell
biology and osseous physiology must be considered as a source for additional
clues of improving implant success. The cellular basis for bone formation and
maintenance of bone mass should be considered in any future synergistic
combination of tissue engineering principles and biointegration of alloplastic
materials. The regulation of cellular activity should be the guide to the
development of novel strategies for improving tissue integration of dental
prostheses.
Eckert SE, Wollan PC31 reported a retrospective study describing the
results for implant survival, implant fracture rate, prosthetic complications, and
design changes that may impact these results.
22

23. Implant survival in this study was independent of anatomic location of
implants. Virtually all clinical performance factors were improved by design
changes in implant restorative components that were brought to market in
early 1991.
Taylor TD86 reported that comparing any surgical or prosthodontic
procedure, osseointegration has offered the greatest improvements are
quality of life for patients who suffer with the effects of an edentulous
condition. Results have been dramatic both functionally and from the aspect
of patient satisfaction. Author critically analyzes the existing literature relative
to prosthodontic problems and complications frequency of complication
versus the perceived potential for complications, including implant failure,
prosthesis misfit, component fracture, and screw loosening.
Masuda T, Yliheikkila PK, Felton DA, et al57 reported that the clinical
success of endosseous implants is associated with the formation and
maintenance of bone at implant surfaces. Histologic analyses have indicated
that bone formation at a variety of implant surfaces is a continuous process
that supports long-term functional integration. Based on in vivo observations
several generalizations have been derived regarding the nature of the
interface. Experimental descriptions indicate that the implant-bone interface
may be characterized in spatial and temporal terms as discontinuous.
Biomechanical tests of the bone associations with implants demonstrate that
the chemical composition and the surface topography of the implant influence
23

24. the rate and extent of bone formation at implant surfaces. The precise
character and functional attributes of this interface are the focus of this
investigation. Many technical difficulties are associated with its structural and
chemical characterization in vivo. Despite the technically difficult nature of this
type of analysis and the limitations of current histologic examinations and
biomechanical tests, in vivo models of osseointegration are necessary
experimental tools for the continued empirical development of clinical implant
application.
Kawahara H, Kawahara D, Takashima Y, et al41 reported the clinical
measurements on gingival indices and morphologic observations were
performed to study and verify the defending mechanism of gingival soft tissue
against
foreign
invasions
from
the
perspective
of
epithelial
adhesion/attachment to implant surfaces in the monkey mandible. The
following zones were observed using scanning electron microscope (1)
plaque zone, suggesting susceptibility of the gingival tissue to bacterial
invasion.( 2) nude zone, demonstrating indirect adhesion of epithelial cells to
the implant surface through the mucous epithelial cells at the cell-implant
interface as compared to cell-cell bonding within the epithelial cell layer. This
study suggested that epithelial cell attachment/adhesion may play a dominant
role in retaining the successful condition of a dental implant.
Cooper LF, Masuada T, Yliheikkila P et al25 reviewed that the
appropriate use of cell culture to evaluate substrate effects on osteoblast
24

25. behavior during the process of osseointegration has been considered in the
context of existing reports. The interactions of osteoblasts with different
substrates can be measured in terms of cytotoxicity, attachment, proliferation,
and differentiation. The osteoblast culture systems that produce an osteoblast
matrix opposing implant material substrates provide one model for evaluating
the implant-bone interface. Alternations in osteoblast behavior at different
culture substrates may reflect clinical determinants of bone formation and
there substrates in vivo; however, cell responses in vitro have not been
compared or correlated with in vivo outcomes. Legitimate interpretations of in
vitro experiments are discussed in terms of practical, technical, and biologic
limitations presented by the cell culture approach. Cell culture provides
access to molecular and cellular information that fosters Nano structural
engineering approaches to implant design and significant hypotheses to be
tested in vivo. In this way, cell culture offers unique insights into the process
and phenomenon of osseointegration.
Fujimoto T, Ueda M84 reported a study to clarify the effects of steroid
administration on the osseointegration of Ti implants.
The results of the study revealed that osseointegration of Ti implants in
the mandible as measured by torque force is not affected as strongly by
steroid administration as is osseointegration in the skeletal bone.
25

26. Kawahara H, Takashima Y, Ong JL42 reported a study to investigate
the effect of plaque extracts on the in vitro response of epithelial-like cells and
the fibroblastic cells to Ti surface.
The result of growth rate assay, cell morphology assay, and adhesive
strength of cells shows that plaque extracts observed to have.
Huja SS, Katona TR39 reported a study using finite element methods
to isolate the effects of callus formation of bonding on the mechanical
environment in implant-supporting bone.
Healing response subsequent to implant placement is characterized by
formation of calluses, rapid remodeling of bone adjacent to the implant, and
an increase in interfacial bond strength.
The results show the importance of the stabilizing roles provided by the
callus and development of bond during the etiological phases of bone healing.
Devlin H, Horner H, Ledgerton D28 the success rate of implant
osseointegration is dependent on many factors such as bone mineral density,
volume and vascularity of bone, implant design, ridge shape, and patient
selection criteria. The authors conducted the study to examine whether a
technique to measure differences in bone mineral density in the maxilla and
26

27. mandible
might
be
useful
to
predict
the
likelihood
of
successful
osseointegration.
Bone densitometry of the jaws was performed with a densitometer, and
bone mineral density was calculated at three regions of the maxilla and one
site in the mandibular body. The results shows significant differences were
found between the mean bone mineral densities of each site when compared
with the three other locations. The mean bone mineral density for the
mandible was twice that of the anterior maxilla. Both were significantly greater
than the bone mineral density of the posterior maxilla including the hared
palate. The bone mineral densities at the three maxillary sites were all highly
correlated.
It is concluded that the posterior maxilla had the lowest bone mineral
density and in certain circumstances before implant insertion, bone
augmentation, or guided tissue regeneration may be advisable to improve the
rate of osseointegration. Because the radiation dose is low, dual energy x-ray
absorptiometry may be a useful noninvasive technique for determining the
bone mineral density before implant insertion.
Almog DM, Sanchez R8 reported that the success of dental implant
treatment relies on a well-developed treatment plan approach.
Historically,
implant placement was guided mainly by residual bone height and width, at
times compromising prosthetic needs.
27

28. Author analyzed the amount of deviation between planned prosthetic
trajectory and residual bone trajectory in and residual bone trajectory in
different areas of the maxillary and mandibular dental arches, by using a
tomographic survey in conjunction with imaging/surgical guides.
Discrepancies between the planned prosthetic and the residual bone
trajectories were greater in the mandibular molar area.
This site was
statistically different from other site groups. Statistically, all other site groups
were not significantly different.
Chang YL, Stanford CM, Keller JC, et al20 reported that when
Hydroxyapatite (HA) used a coating for implants can exhibit varying levels of
interaction with the biologic environment. The crystallinity of the HA-based
coating has been shown to control the rate of dissolution and appears to play
a role initial cellular interaction with the implant surfaces. An osteoblastic cell
attachment assay was employed to examine the cell attachment to untreated
and pretreated (pH5.21, 24 hours) titanium and HA coatings of less (50%)
medium (75%) and high (90%) crystallinity. A slightly higher percentage of
cell attachment (%CA) was found on untreated and pretreated HA surface as
compared to the titanium surface. No significant difference could be found in
the %CA between the 3 levels of crystallinity. However, higher levels of % CA
were observed on pretreated HA surfaces than untreated HA surfaces.
Elevated calcium and phosphate levels in culture medium did not have any
effect on cell attachment.
Scanning electron microscopic examinations
28

29. revealed surface degradation of the HA coating following pretreatment in the
simulated inflammatory media. The results suggest that the altered surface
topography may influence the initial cell attachment to HA surfaces.
Orsini G, Assenza B, Scarano A, et al67 reported that the implant
surface analyses were performed on 10 machined implants and on 10
sandblasted and acid-etched implants. Subsequently, sandblasted and acidetched implant cytotoxicity, morphologic differences between cells adhering to
the machined implant surfaces, and cell anchorage between cells adhering to
the machined implant surfaces, and cell anchorage to sandblasted and acidetched implant surfaces were evaluated. Results indicated that acid etching
with 1% hydrofluoric acid / 30% nitric acid after sandblasting eliminated
residual alumina particles. The average roughness of sandblasted and acid
etched surfaces was about 2.15µm.
Cytotoxicity tests showed that
sandblasted and acid-etched implants had non-cytotoxic cellular effects and
appeared to be biocompatible. Scanning electron microscopic examination
showed that the surface roughness produced by sandblasting and acid
etching could affect cell adhesion mechanisms. Osteoblast-like cells adhering
to the sandblasted and acid-etched surfaces showed an irregular morphology
and many pseudopodia. These morphologic irregularities could improve initial
cell anchorage, providing better osseointegration for sandblasted and acidetched implants.
29

30. Placko HE, Mishra S, Weimer JJ, et al69 examined the effects of
different treatments (polished, electropolished, and grit-blasted) on the
surface morphology and chemistry of commercially pure titanium and
titanium-6% aluminum-4% vanadium. The structure and composition of the
surfaces were evaluated using scanning electron microscopy, atomic force
microscopy, energy dispersive spectroscopy, Auger microprobe analysis, and
x-ray photoelectron spectroscopy. Surface roughness values at large scales
were nearly identical for grit-blasted and electropolished samples, while at
smaller scales, electropolished and polished samples had nearly identical
quantitative roughness values. The surface oxide compositions were found to
be primarily titanium dioxide on both materials for all surface treatments. No
vanadium was seen with either x-ray photoelectron spectroscopy or Auger
microprobe analysis for the alloy, indicating a possible surface depletion.
Calcium was present on the grit-blasted samples, and calcium and chlorine
were detected on the electropolished samples.
Squier RS, Agar JR, Duncan JP et al83 reported that the dental
evaluation of the retentive capabilities of luting agents when used between
metal components, such as cast metal restorations cemented onto machined
metal implant abutments.
Author compared the retentive strengths of 5
different classes of luting agents used to cement cast noble metal alloy metal
alloy crowns to 8-degree machined titanium cementable implant abutments
from the Straumann ITI implant System. Sixty prefabricated 5.5-mm solid
titanium implant abutments and implants were used; 30 received the standard
30

31. surface preparation and the other 30 received an anodized surface
preparation.
Anodized implant components were used to reflect current
implant marketing. Sixty castings were fabricated and randomly paired with
an abutment and implant. A total of 12 casings were cemented on to the
implant-abutment assembles for each of the 5 different luting agents (zinc
phosphate, resin composite, glass ionomer, resin-reinforced glass ionomer,
and zinc oxide-non-eugenol.) A statistically significant difference was found
between the 5 cements. Of the cements used, resin composite demonstrated
the highest mean retentive strength, Zinc phosphate and resin-reinforced
glass-ionomer cements were the next most retentive, while glass-ionomer and
zinc oxide-non-eugenol cements demonstrated minimal retention. In addition,
retention was not altered by the use of an anodized abutment surface.
Ramp LC, Jeffcoat RL70 conducted research into the formation,
destruction, and adaptation of bone around implants would benefit from a
sensitive, nondestructive, noninvasive, and quantitative technique to assess
the bone-implant interface. They hypothesized that osseointegration can be
quantified by sensing the mechanical impedance (or micromobility) of the
implant when it is subjected to minute vibratory forces superimposed upon a
quasi-static preload. To test this hypothesis, titanium root-form implants were
placed in the mandibles of 4 Walker hounds and allowed to heal submerged
for
3
months.
The
implants
were
exposed
and
characterized
for
osseointegration using clinical observations, quantitative radiography, and a
custom-designed impedance instrument. Subsequently, arbitrarily selected
31

32. implants were ligated to induce bone loss and examined monthly over a 6month study period. Following the terminal examination and euthanasia,
quantitative histologic measurements were made of bone adjacent to the
implant, including estimates of both crestal bone height and the percent bone
(bone fraction). Linearized dynamic parameters (effective stiffness and
effective damping) correlated well with radiographic and histologic measures
of bony support. The presence of nonlinear stiffness was clearly associated
with a bimodal “Clinical impression” of osseointegration. These results confirm
that, in this animal model, mechanical impedance can be used as a measure
of implant osseointegration.
Lumbikanonda N, Sammons R52 conducted a study on bone cell
interactions with smooth titanium, titanium dioxide-blasted, titanium plasmasprayed, and hydroxyapatite plasma-sprayed implants, as manufactured for
clinical use, were compared. Implants were exposed to neonatal rat
osteoblast cells in suspension for a 20-minute period and, by means of
scanning electron microscopy, attached cells were classified according to
stage of attachment. Quantitative analysis showed that cells spread most
quickly on the titanium plasma-sprayed implants. Fully spread cells on the
smooth titanium implants were closely adherent to the surface, while on the
titanium dioxide-blasted surface they showed no adaptation to surface
irregularities. On the hydroxyapatite-coated implants, cells adhered closely
only to smooth areas. To avoid the use of proteolytic enzymes for cell
derivation, the authors developed a novel organ culture system in which the
32

33. implant was contained in a nylon pocket surrounded by bone fragments,
permitting cells to migrate onto the implant surface. Cultures were maintained
for up to 4 weeks, allowing comparison of cell migration, proliferation, and
differentiation on the implant surfaces.
Hermann JS, Schoolfield JD, Nummikoski PV, et al37 showed
generally that endosseous implants can be, placed according to a
nonsubmerged or a submerged technique and in 1-piece or 2-piece
configurations. Recently, it has been shown that peri-implant crestal bone
reactions differ significantly radiographically as well as histometrically under
such conditions and are dependent on a rough/smooth implant border in 1piece implants and on the location of a microgap (interface) between the
implant and the abutment/restoration in 2-piece configurations. The authors
studied to evaluate whether standardized radiography as a noninvasive
clinical diagnostic method correlates with peri-implant crestal bone levels as
determined by histometric analysis.
These data demonstrates that standardized periapical radiography can
evaluate crestal bone levels around implants clinically accurately (within
0.2mm) in a high percentage (89%) of cases. These findings are significant
because crestal bone levels can be determined using a noninvasive technique
and block sectioning or sacrifice of the animal subject is not required. In
addition, longitudinal evaluations can be made accurately such that bone
changes over various time periods can be assessed. Such analyses may
33

34. prove beneficial when trying to distinguish physiologic changes from
pathologic changes or when trying to determine causes and effects of bone
changes around dental implants.
Lim YJ, Oshida Y, Andres C, et al49 the attachment of cells to
titanium surfaces is an important phenomenon in the area of clinical implant
dentistry. A major consideration in designing implants has been to produce
surfaces that promote desirable responses in the cells and tissues. To
achieve these requirements, the titanium implant surface can be modified in
various ways. Research was designed to elucidate the relationship between
surface roughness and contact angle of various engineered titanium surfaces
of commercially pure titanium, titanium-aluminum-vanadium alloy (TI-6AI-4V),
and titanium-nickel (TiNi) alloy. It was found that: (1) There were no significant
differences in contact angles among the media; (2) for commercially pure
titanium, a combined treatment (hydrofluoric acid/nitric acid/water →sodium
hydroxide →oxidation) showed the lowest Ө, while the surface treated with
sulfuric acid showed the highest value; (3) for all commercially pure titanium
samples, when Ө, is greater than 45 degrees, the contact angle increases
linearly with Ra (hydrophobic nature) and the surface is covered with rutiletype oxide only, while the contact angle decreases linearly with Ra when Ө is
less than 45 degrees (hydrophilic nature) and the surface is covered with a
mixture of rutile and anatase oxides; and (4) a similar trend was found on Ti6AI-AV and TiNi surfaces.
34

35. Drake DR, Paul J, Keller JC30 conducted a study to assess the effects
of modifying titanium surfaces, in terms of wettability, roughness and mode of
sterilization, on the ability of the oral bacterium Streptococcus sanguis to
colonize. An in vitro model system was developed. All surfaces were
colonized by the bacteria, but to significantly different levels. Titanium
samples that exhibited rough or hydrophobic (low wettability) surfaces, along
with all autoclaved surfaces, were preferentially colonized. Titanium surfaces
that had been repeatedly autoclaved were colonized with the levels of
bacteria 3 to 4 orders of magnitude higher that other modes of sterilization.
This may have implications relative to the commonly used method of
autoclaving titanium implants, which may ultimately enhance bacterial biofilm
formation on these surfaces.
Zhu X, Kim K, Ong JL et al94 reported a study on the effect of
phosphoric acid solution on the anodic oxide film of titanium. Commercially
pure grade 2 titanium specimens were prepared and anodized in phosphoric
acid solution at a constant current density (70A/m 2). Specimens were
evaluated by means of scanning electron microscopy, x-ray diffraction
analysis, electron probe microanalysis, energy-dispersive spectroscopy,
profilometry, and atomic force microscopy. The anodic oxide film was
observed to consist of a porous or non-uniform layer. X-ray diffraction showed
anatase and amorphous oxide, with the incorporation of phosphorus. The
degree of oxide crystallinity was observed to increase with an increase in
voltage but decreased as the electrolyte concentration was increased. In
35

36. addition, the concentration of phosphorus also increased as the electrolyte
concentration and voltage increased and concluded that Electrolyte
concentration and voltage play an important role in governing the anodic
oxide thickness, composition, and degree of oxide crystallinity.
Ma J, Sorsa T, Kononen M et al54 Cellular fibronectin staining is
decreased
in
adult
Periodontitis,
which
implies
elastase–mediated
degradation of periodontal tissues. The authors studied to determine whether
failing dental implants display similar changes. Cellular fibronectin and its
integrin receptors were identified by immunohistochemistry and quantified by
computerized image analysis. The results showed that cellular fibronectin was
found in blood vessel walls, epithelial basement membranes, and fibroblasts.
Cellular fibronectin staining was increased around failing dental
implants but decreased in adult Periodontitis compared to healthy controls.
The distribution of integrin receptor subunits α4, α5 and β1 of cellular
fibronectin was similar in failing dental implants. The pathomechanisms in
adult Periodontitis and failing dental implants seem to differ. They concluded
that adult Periodontitis is characterized by proteolysis/ loss of cellular
fibronectin, whereas failing dental implants are characterized by increased
cellular fibronectin deposition, probably as a result of titanium-induced local
synthesis and relatively modest degradation.
36

37. Geurs NC, Jeffcoat RL, McGlumphy EA, et al35 conducted a study
on 2 design related independent variables control at 2 levels. Geometry
(Threaded/ Cylindrical) and coating (TPS or HA) using periotest instrument.
Micromobility by perio test appears to measure differences in implant
behaviour that are undetectable by more conventional means. The author‟s
hypothesis of the design of implant influences the time course of
osseointegration showed that HA-coated implants consistently exhibited a
more rapid early decrease I mobility than the identical geometry of TPS
Implants.
37

38. DEVELOPMENT OF CONCEPT
The initial concept of osseointegration stemmed from vital microscopic
studies of the bone marrow of the rabbit fibula, which was uncovered for
visual inspection in a modified intravital microscope at high resolution in
accordance with a very gentle surgical preparation technique. With special
instrumentation, the marrow could be studied in transillumination in vivo, and
in situ, after the covering bone was ground down to a thickness of only 10 to
20 μm. Circulation was maintained in this thin layer of bone and with very few
signs of microvascular damage, which is the earliest and most sensitive
indication of tissue injury. These intravascular studies of bone marrow
circulation also revealed the intimate circulatory connection among marrow,
bone and joint tissue compartments.15
A series of in vivo studies on bone, marrow, and joint tissue were
performed with particular emphasis on tissue reaction to various kinds of
injury: Mechanical, Thermal, Chemical, and Rheologic. The studies were also
concerned with the various therapeutic possibilities to minimize the effect of
such trauma and further sought to identify additional traumatic factors such as
wound disinfectants and to explore the development of procedures that
promote predictable healing of differentiated tissues.
Long–term in vivo microscopic studies of bone and marrow response to
implanted titanium chambers of a screw shaped design were also performed.
38

39. These studies in the early 1960s strongly suggested the possibility of
osseointegration since the optical chambers could not be removed from the
adjacent bone once they had healed in. They observed that the titanium
chambers were inseparably incorporated within the bone tissue, which
actually grew into very thin spaces in the titanium. Interdisciplinary clinical
cooperation with plastic surgeons and otolaryngologists enabled them to
study the repair of mandibular defects and replacement of ossicles by means
of autologous bone grafts. Desired anatomic shapes of bone grafts were
preformed in rabbits and dogs and subsequently applied clinically with longterm follow- up. In an extensive series, the repair of major mandibular and
tibial defects in dogs were studied the most successful being the one based
on the prior integration of titanium fixtures on both sides of the defect to be
created later. When the fixtures had become safely incorporated within the
bone, a defect was created, titanium splints maintained the topographical
relation between the cut edges, and an autologous graft of trabecular bone
and marrow compensated for the tissue defect.
Separate studies were performed on the healing and anchorage
stability of titanium tooth root implants or fixtures of various sizes and designs.
It was found that when such an implant was introduced into the marrows
cavity, and followed by an adequate immobilized healing period, a shell of
compact cortical bone was formed around the implant without any apparent
soft tissue intervention between normal bone and the surface of the implant.
39

40. A direct correlation was observed among microtopography of the
titanium surface, the absence of contamination, the preparatory handling of
the bone site, and the histologic pattern elicited in the adjacent bone. In a
separate study fixtures were installed in the tail vertebrae of dogs with
successful integration even when abutments were allowed to pierce through
the skin.
On the basis of the findings in these experimental studies, they decided
to perform a series of experiments that would enable them to develop clinical
reconstructive procedures for the treatment of major mandibular defects,
including advanced edentulous states. It was felt that both osseointegration
and autologous bone graft would be useful in these clinical defect situations.
Teeth were extracted in dogs and replaced by osseointegrated screwshaped titanium implants. Fixed prostheses were connected after an initial
healing time of 3 to 4 months without loading; the fixtures were allowed to
heal under a mucoperiosteal flap, which was then pierced for abutment
connection and subsequent prosthetic treatment.5
Different types of prosthetic designs were used. Radiologic and
histologic analyses of the anchoring tissues showed that integration could be
maintained for 10 years in dogs with healthy bone tissue and with out
progressive inflammatory reactions.
40

41. At the time the animals were killed, the titanium fixtures could not be
removed from the host bone unless cut away. The anchorage capacity of the
separate implants was determined as 100kg in the lower jaw and 30 to 50 Kg
in the upper jaw. Efforts to extract the implants led to fractures in the jaw bone
per se, not at the actual interface. Microradiographic analyses revealed load–
related remodeling of the jaw bone around the implant, even in those cases
where the implants were in very close proximity to the nasal and sinus
mucoperiosteum at installation.40
These long-term experimental studies suggested the possibility of
achieving and maintaining bone anchorage under unlimited loading of dental
prostheses in the dog attached to osseointegrated fixtures. Soft tissue
penetration of titanium abutments could be used without untoward reactions in
edentulous jaws, and also for the attachment of titanium chambers for vital
microscopy in rabbit and dog tibiae.68
Later
vital
microscopic
studies
were
carried
out
on
human
microcirculation and intravascular behavior of blood cells at high resolution by
means of an implanted optical titanium chamber in a twin – pedicled skin tube
on the inside of the left upper arm of healthy volunteers. The tissues reaction
as revealed by intravascular rheologic phenomenon was studied in long-term
experiments in these chambers with out indications of inflammatory
processes.82 It therefore, seemed reasonable to assume that bone anchorage
41

42. according to the principle of osseointegration might also work in humans, and
they treated their first- edentulous patients in 1965.
Definition of osseointegration:
Previous definitions of Osseointegration have stated that the interface
between the metal implant and the host should consist entirely of bone
without any intervening connective tissue. Usually, when used in this context,
the word “bone is interpreted as meaning calcified osseous matrix. Such an
interpretation or definition is difficult to accept because bone tissue simply
does not react to any implant or foreign body or to any surgical repairing
situation by laying down a wall composed entirely of calcified matrix without
any accompanying soft tissue.63
42

43. In addition, the alveolar host bone-to-metal implant interface, if it
follows the traditional response to orthopedic metal devices, will be a dynamic
one, subject to many changes in character, i.e., viable bone having partially
cellular marrow-vascular spaces and partially inert non-viable matrix could
contribute to the bone-to-metal interface.34
Some investigators believe that the definition of “osseointegration” is to
refer to the osseous tissue lying next to the metal implant as containing all
aspects of bone i.e., marrow-vascular spaces, hemopoietic tissue, fatty tissue,
and connective tissue type I, or, to state it more simply, “calcified bone and all
its accompanying soft tissue elements”. If this is the intent of the definition, we
are dealing with something that we can accept and that we can use as a basis
for research investigation.40 But to say that solid, calcified bone without any
intervening marrow-vascular space, connective tissue space, or fatty or
hemopoietic tissue is going to be juxtaposed onto the intrabony implants is to
propose a situation that is difficult to achieve and unrealistic in terms of
previous orthopedic and bone research. To expect the randomly arranged,
fine cancellous bone pattern existing in edentulous ridges to respond with the
formation of 100% dense bone to satisfy the old definition of osseointegration
in not reasonable from the standpoint of osseous dynamics.68, 82.
43

44. Instead, one would expect a healthy bone response to be a laying
down of calcified and non – calcified osseous matrix on the surface of the
implant. This matrix would in turn be subject to remodeling, modification, and
resorption, depending on the demands of function that later would be placed
on the marrow vascular spaces, connective tissue, Vascular tissue, and soft
as well as hard tissue areas. This type of osseous tissue is responsive in the
long- term demands of function that may be placed colossally on the
appliance and tends to lead to a healthy clinical situation.82
Osseointegration is based on the idea of a stable bone anchorage of
an oral implant in contrast to a soft – tissue anchorage of the same that so
known to function poorly over long terms of follow- up . This may seem
peculiar as the tooth itself is anchored in soft tissue. However, a tooth is
attached with a highly differentiated periodontal ligament, in sharp contrast to
the poorly organized soft –tissue attachment of an oral implant. In fact, softtissue of a scar – like type is what develops around
foreign materials such
as metals inserted in the oral cavity, attempts to define osseointegration
based on histologic criteria have failed and today the only acceptable
definition seems to be based on confirmed and maintained implant stability as
suggested by zarb & Alberktsson, 1991.
“Osseointegration is process where by clinically asymptomatic rigid
fixation of alloplastic materials is achieved, and maintained, in bone during
functional loading”.
44

45. Definition of Branemark5
“Osseointegration is a direct structural and functional connection
between ordered, living bone and the surface of a load-carrying implant”. This
definition however does not survive the scrutiny of time. In the future, it seems
as a structurally based definition must identify the minimal contact zone
between bone and implant and if a functional connection exists it has to be
demonstrated with more sensible instruments than that of a proved longterm function .In fact, in 1983 skalak pointed out that a mere bony in growth
into the irregularities of the implant without any true functional connection (for
example, via physical and chemical bonds) would be sufficient to carry the
loads put on the oral implant devices . There have been various attempts to
separate a structural and functional bone connection although different
terminologies have been used by. Osborne & Newesly referred to materials
as being bioinert (for example, titanium and carbon) and bioactive (glass
ceramics and various types of calcium phosphates) where the former
materials
would
be
structurally connected
to
bone
and
the
latter
physicochemically bound.40 Meffert et al. differentiated between what was
referred to as “adaptive osseointegration” and “biointegration” the latter type
of connection being typical for calcium phosphates
(such as hydroxyapatite)
and representing a true chemical bond.68
45

46. OSSEOINTEGRATION
Concept of Bony
Anohorage
Branemark (1969)
FIBROINTEGRATION
Concept of soft tissue
anchorage
Linkow (1970), James
(1975), Weiss (1986)
46

47. CONCEPT OF OSSEOINTEGRATION
Dr. Per-Ingvar Branemark
Orthopaedic Surgeon
Professor University of Goteborg, Sweden.
47

48. Historical Background
The basic science and clinical research work of Branemark and his
colleagues appears to have reconciled these four components into a clinically
successful equation. This was first described in a 1977 monograph that was
also published as supplement number 16 to the Scandinavian journal of
Plastic and Reconstructive Surgery. The Branemark data were presented in
1982 to the North American Oral Surgeons and Prosthodontists representing
academic institutions at the seminal Toronto Conference on Osseointegration
in Clinical Dentistry. The quality of the Branemark research combined with the
documented long-term efficacy of his treatment results, articulated a very
strong case for the osseointegration method.
In 1979, a University of Toronto faculty of Dentistry Osseointegration
Research Project was undertaken, supported by funds from the Ontario
Ministry of Health.
1.
In a landmark paper published in 1969, Branemark et al described the
phenomenon for submerged titanium implants from a clinical point of
view and with decalcified histologic sections.
2.
Seven years later, Schroeder et al provided the first true histologic
evidence of direct bone-to-implant contact for nonsubmerged titanium
implants using nondecalcified histologic sections with the titanium
48

49. implants still presents in the specimens. Later, these authors created
the terms osseointegration and functional ankylosis.
3.
Adell
et
al
first
reported
the
long-term
documentation
of
osseointegrated implants in a retrospective clinical study treating fully
edentulous patients with Branemark implants. The authors reported
estimated implant survival rates of 86% in the mandible and 78% in the
maxilla at 15 years.
4.
Similar results of retrospective studies have also been reported for
nonsubmerged ITI implants placed in fully edentulous patients by
Babbush et al, Bruggenkate et al and Krekeler et al.
5.
Zarb and Schmitt applied strict criteria for success, the examination up
to 5 years demonstrated success rates above 95%. Mean success
rates above 90% have also been reported for Branemark implants.
6.
Roberts et al suggested that most cortical grafts are never fully
resorbed but remain admixtures of dead bone despite developing net
bone strengths equal to adjacent nongrafted areas. Devitalized bone
could possibly lead to loss of osseointegration.
7.
Carter et al have shown that compressive micro damage results from
oblique fractures that run through cellular lacunae and canaliculi,
49

50. stimulating an extensive cellular response to repair. Repair capability is
impaired in devitalized bone or alloplast combined grafts. This
mechanism may help to explain findings reported by Roberts et al that
early loading of dental implants led to remodelling of devitalized bone,
undermining the periosteal margin integrity of titanium implants.
8.
Carlsson et al showed that osseointegration does not occur unless the
osseous gap between titanium and the bony surface is less than about
0.2 mm. Except through the cortical portion of the graft, this close
proximity is doubtful in bone graft cases.
Cellular Background to Osseointegration:
The conditions for a proper bone response to occur include the
presence of adequate cells, an adequate nutrition to these cells and an
adequate stimulus for bone repair. The adequate cells are differentiated bone
cells (osteoblast, osteoclast and osteocyte) on the one hand and
undifferentiated cells that may be stimulated in the direction of an osteogenic
induction on the other. In reality bone healing is dependent not only on the
recruitment of new bone tissue, but also on an appropriate amount of newly
formed soft-tissue, including capillaries, to take but one example. The
inevitable trauma to bone at every surgical procedure involving that tissue will
trigger not only the formation of new bone, but also the formation of various
soft tissues.
50

51. The balance between the different tissue elements involved in bone
repair is influenced by mediators elicited from the cells. There are antocrine
as well as paracrine control mechanisms. This delicate balance may be easily
Soft tissue
interface
Cortical
bone
Spongy
bone
51

52. disturbed by external influences, for instance movements that will turn the
balance in favor of new soft tissue formation instead of bone. Other known
circumstances that affect bone healing are PH or 0 2 saturation. That the
adequate stimulus for bone repair is „injury‟ should not lead to the false
conclusion that more injury will result in a greater healing response. Too much
injury will result in permanent damage to the repair tissues and healing will not
start.
Stages of Osseointegration:
Direct bone healing, as it occurs in defects, primary fracture healing
and in Osseointegration is activated by any lesion of the pre-existing bone
matrix. When the matrix is exposed to extracellular fluid, noncollagenous
proteins and growth factors are set free and activate bone repair.
Once activated, osseointegration follows a common, biologically
determined program that is subdivided in to 3 stages:
1. Incorporation by woven bone formation.
2. Adaptation of bone mass to load (lamellar and parallel-fibered bone
deposition); and
3. Adaptation of bone structure to load (bone remodeling).
52

53. INCORPORATION BY WOVEN BONE FORMATION:
The first bone tissue formed is woven bone. It is primitive type of bone
tissue and characterized by a random, felt – like orientation of its collagen,
fibrils, and numerous irregularly shaped osteocytes and, at the beginning, a
relatively low mineral density. It grows by forming a scaffold of rods and plates
and thus is able to spread out into the surrounding tissue at a relatively rapid
rate. The formation of the primary scaffold is coupled with the elaboration of
the vascular net and results in the formation of a primary spongiosa that can
bridge gaps of less than 1 mm within a couple of days. Woven bone usually
starts growing from the surrounding bone towards the implant, except in
narrow gaps, where it is simultaneously deposited upon the implant surface.
Woven bone formation dominates the first 4 to 6 weeks after surgery.
Parallel fiber
arrangement
Complete fiber
encapsulation
53

54. ADAPTATION OF BONE MASS TO LOAD:
Starting in the second month, the microscopic structure of newly
formed bone changes, either towards the well-known lamellar bone or
towards an equally important but less known modification called parallel fibered bone. Lamellar bone is the most elaborate type of bone tissue.
Packing of the collagen fibrils into parallel layers with alternating course gives
it the highest ultimate strength. Parallel - fibered bone is an intermediate
between woven and lamellar bone.
Three surfaces are qualified as a solid base for deposition of parallel
fibered and lamellar bone.
1.
Woven bone formed in the first period of Osseointegration: Deposition
of more mature bone on the initially formed scaffold results in
reinforcement and often concentrates on the areas where major forces
are transferred from the implant to the surrounding original bone.
2.
Pre – existing or pristine bone surface: Frequently, the trabeculae
become necrotic due to the temporary interruption of the blood supply
at surgery. Reinforcement by a coating with new viable bone
compensates for the loss in bone quality and again may reflect the
preferential strain pattern resulting from functional load.
54

55. 3.
The implant surface: Bone deposition in this site increases the bone –
implant interface and thus enlarges the load – transmitting surface.
Extension of the bone implant interface and reinforcement of pre –
existing and initially formed bone compartments are considered to represent
an adaptation of the bone mass to load.
ADAPTATION OF BONE STRUCTURE TO LOAD:
Bone remodeling characterizes the last stage of osseointegration. It
starts around the 3rd month and, after several weeks of increasingly high
activity, slows down again, but continues for the rest of life. In cortical, as well
as in cancellous bone, remodeling occurs in discrete units, often called a bone
multicellular unit. Remodeling starts with osteoclastic resorption, followed by
lamellar bone deposition. Resorption and formation are coupled in space and
time. In cortical bone, a bone multicellular unit consists of a squad of
osteoclasts that form a sort of drill – head and produce a cylindrical resorption
canal with a diameter equal to an osteon, that is, 150 – 200µm. The cutting
cone advances with a speed of about 50µm per day, and is followed by a
vascular loop, accompanied by perivascular osteoprogenitor cells. About
100µm behind the osteoclasts, the first osteoblasts line up upon the wall of
the resorption canal and begin to deposit concentric layers of lamellar bone.
After 2 – 4 months, the new osteon is completed. In the healthy skeleton,
resorption and formation are not only coupled, but also balanced, thus
maintaining the skeletal mass over a longer time period. If formation does not
55

56. match resorption, a local deficit in bone mass occurs that accumulates with
time and may cause osteoporosis.
Mechanism of Osseointegration:
Phase
1. Inflammatory phase
Timing
Day 1 – 10
Specific Occurrence
Adsorption of plasma proteins.
Platelet aggregation & activation.
Clotting cascade activation.
Cytokine release.
Non-specific cellular inflammatory
response.
Specific cellular inflammatory response.
Macrophage mediated inflammation.
2. Proliferative phase
Day 3 – 42
Neovascularization.
Differentiation, proliferation and activation
of cells.
Production
of
immature
connective
tissue matrix.
3. Maturation phase
After day 28
Remodeling of the immature
Bone matrix with coupled resorption and
deposition of bone.
Bone remodeling in response to implant
loading.
Physiological bone recession.
56

57. Key factors responsible for successful Osseointegration / Factors
ensuring bone anchorage:
There are several reasons for primary as well as secondary failure of
osseointegration. These failures may be attributed to an inadequate control of
the six different factors known to be important for the establishment of a
reliable, long-term osseous anchorage of an implanted device. These factors
are:
1. Implant material biocompatibility.
2. Implant design characteristics.
3. Implant surface characteristics.
4. State of the implantation or host bed.
5. Surgical considerations.
6. Loading conditions.
There is a need to control these factors more or less simultaneously to
achieve the desirable goal of a direct bone anchorage.
57

58. Implant material biocompatibility:
Biological
biocompatibility
Biotolerant
Chemical composition
Metals
Ceramics
Polymers
Polyethylene
Cobalt-chromium
Polyamide
alloys
Poly-methyl
Stainless steel
methacrylate
Zirconium
Poly-tetrafluoro
Niobium
ethylene
Tantalum
Bioinert
Gold
Poly-urethane
Commercially
pure
Aluminum oxide
titanium( Zirconium oxide
CPTi)
Titanium alloy
(Ti-6Al-4V)
Bioactive
Hydroxyapatite
Tricalcium
phosphate
Calcium
pyrophosphate
Fluorapatite
Carbon: vitreous,
pyrolytic
Bioglass
Commercially pure (Cp) titanium, niobium and possibly tantalum are
known to be most well accepted in bone tissue. The reason for the good
acceptance of these metals does probably relate to the fact that they are
covered with a very adherent self-repairing oxide layer, which has an
58

59. excellent resistance to corrosion. Whereas the load-bearing capacity of Cp
titanium is sufficiently documented in the case of oral implants, there is less
known about niobium in this aspect. Metals such as different cobalt-chromemolybdenum alloys and stainless steels have demonstrated less good take in
the bone bed. A significantly impaired interfacial bone formation compared to
Cp titanium has been found with titanium-6 aluminium-4 vanadium alloy. The
concern with metal alloys is that one alloy component may leak out in
concentrations high enough to cause local or systemic side effects. However,
whether these and other differences between Cp titanium on the one hand
and various alloys on the other are of a practical clinical importance or of only
a theoretical one is uncertain, which is why the alloys have been placed in the
yellow zone. In the red zone, definitely, are metals such as copper and silver
that are known to result in a permanent soft tissue attachment because of
poor
biocompatibility.
Ceramics
such
as
the
calcium
phosphate
Hydroxyapatite (HA) should definitely be in the green zone, whereas various
types of aluminium oxides are in the yellow region due to insufficient
documentation.
Albrektsson et al4,5 demonstrated that the zone closest to the titanium
oxide surface consisted of proteoglycans of a width of 200 to 400 A 0 calcified
tissue was seen in direct contact (resolution level 30 to 50A 0) with the implant.
Collagen filaments were seen in the proteoglycan layer, but never closer than
200 A0 from the implant. Collagen bundles were, generally, not seen until a
distance of minimally 1000A0 from the metal. Zirconium was surrounded by
59

60. proteoglycan coats of 300 to 500 A0 and collagen bundles were not seen until
a few thousand A0. As proteoglycan layers of 100 to 200 A0 thickness are
seen in the normal tissue where no implant has been inserted, this points to
commercially pure titanium being more natural than zirconium and,
presumably, of better biocompatibility.
Polymers are not used because of their Inferior mechanical properties
and lack of adhesion to living tissues due to adverse immunological reaction.
They are limited to shock absorbing components i.e., supra structure
component.
Implant design characteristic:
Implant design refers to the 3 dimensional structure of the implant i.e.,
form, shape, configuration, geometry, surface macro structure, and macro
irregularities.
“Precision fit in the vital bone” leads to osseointegration.
There is, at present, sufficient long-term documentation only on
threaded types of oral implants that have been demonstrated to function for
decades without clinical problems. Unthreaded implants may function too,
even if there is a total lack of positive documentation with respect to bone
saucerization, a problem that caused failure of many early types of oral
implants.
60

61. Various implant designs are:
1. Cylindrical
2. Screw shaped implants
3. Threaded
4. Non threaded
Cylindrical implants / press fit implants:
Leads to severe bone resorption due to micro movement of the implant in
the bone. Alberktsson in 1993 reported that continuing bone saucerization of
1mm – first year, 0.5 mm annually and there after increasing rate of resorption
up to 5 year follow up.
Threaded implants:
Documentation for long term clinical function.
Alteration in the design, size and pitch of the threads can influence the
long term osseointegration.
61

62. NON THREADED
THREADED
62

63. Advantages of threaded implants:
More functional area for stress load distribution than the cylindrical
implants.
Threads improve the primary implant stability and avoid micro
movement of the implants till osseointegration is achieved.
The various forms of threads are:
1. Standard v – thread
2. Square thread
3. Buttress thread
Implant surface characteristic:
Implant surface characteristics
Physical properties
Topographic properties
Implant surface texture & roughness
surface energy
and charge
Physiochemical
properties
Implant surface chemistry
63

64. Surface topography includes the orientation of irregularities and
degree of roughness of the surface.
Orientation of irregularities may give isotopic surface & anisotropic
surface.
Wennerberg (1996) Ivanoff (2001) reported that better bone fixation
(osseointegration) will be achieved with implants with an enlarged isotropic
surface as compared to implant with turned anisotropic surface structure.
Different machining process results in different surface topographies:
1. Turned surface / machined surface.
2. Acid etch surface – Hcl & H2 SO4 .
3. Blasted surface - Tio2/Al2 O3 particles .
4. Blasted + Acid etch surface(SLA surface )
AL2O3 Particles & Hcl & H2SO4
Tri calcium phosphate & HF & NO3
5. Hydroxyapatite coated surface (HA)
6. Titanium plasma sprayed surface (TPS)
7. Oxidized surface
8. Doped surface.
9. Nanosized hydroxyapatite coated surfaces.
64

65. With
respect
to
the
surface
topography
there
is
clear
documentation that most smooth surfaces do not result in an acceptable bone
cell adhesion. Such implants do therefore end up as being anchored in soft
tissue despite the material used. Clinical failure would be prone to occur.
Some micro irregularities seem to be necessary for a proper cellular adhesion
even if the optimal surface topography remains to be described.
With a
gradual increase of the surface topographical irregularities, problems due to
an increased ionic leakage are prone to occur. With plasma-sprayed titanium
surfaces for instance, more than 1600 ppm titanium has been reported in
implant-adjacent haversian systems, probably resulting in an impairment of
osteogenesis.
Another surface parameter is the energy state where a high surface
energy has been regarded as positive for implant take due to an alleged,
improved cellular attachment. One practical way of increasing the surface
energy is the use of glow discharge (Plasma cleaning).
Carlsson et al published evidence of superiority of the threaded design
in osseointegration compared with plates and various irregular implant
shapes. Kasemo and Lausmaa have recently summarized to-date viewpoints
on the implant surface and made three important conclusions:
65

66. (1)
The surface status of a particular implant material may vary widely
depending on its preparation and handling history.
(2)
The surface status of implants is expected to be important for in
vivo function and should, therefore, controlled and standardized.
(3)
It is usually not possible to predict how a change in surface status
will affect the long-term in vivo function of an implant.
These conclusions emphasize the importance of either keeping to
well documented surfaces and if a new, seemingly identical, implant is
introduced it is surely not sufficient to only describe its surface topography
and relate this to an assumed future implant success. It is also important to
keep implants scrupulously free of contaminating over layers at the instant of
their biological placement. One practical approach to assure such a clean
surface would be the use of radio-frequency glow-discharge (plasma
cleaning) for implant sterilization.
Additive surface treatment:
Eg: Titanium plasma spraying (TPS) Hydroxyapatite (HA) coating.
Subtractive surface treatment:
Eg: Blasting with titanium oxide / aluminum oxide and acid etching.
Modified surface treatment:
Eg: Oxidized surface treatment
Laser treatment
Ion implantation.
66

67. Machined / turned surfaces:
Moderately rough implant surfaces shows faster & firmer bone integration.
Roughness parameter (Sa)
0.04 –0.4µm – smooth
0.5 – 1.0 µm – minimally rough
1.0 – 2.0 m – moderately rough.
> 2.0µm – rough
Wennerberg (1996) reported that moderately rough implants developed
the best bone fixation as described by peak removal torque & bone to implant
contact.
IN VIVO STUDIES shows that smooth surface (< 0.2µm) will lead to
soft tissue formation and no bone cell adhesion which causes clinical failure of
the implant.
Moderately rough surface shows more bone in contact with implant
which leads to better osseointegration. Carlson et al 1988, Gotfredsen (2000)
reported positive correlation between increasing surface roughness & degree
of implant incorporation (osseointegration).
67

68. Advantages of moderately rough surface:
Faster osseointegration, retention of the fibrin clot, osteoconductive
scaffold, osteoprogenitor cell migration
Increase rate and extent of bone accumulation leads to contact
osteogenesis.
Increased surface area renders greater osteoblastic proliferation,
differentiation of surface adherent cell.
Increased cell attachment, growth and differentiation.
Increased rough surface:
Increased risk of periimplantitis.
Increased risk of ionic leakage / corrosion.
Machined / turned surface:
Cp titanium surface roughness profile 5µm.
Titanium plasma sprayed coating (TPS)
The first rough titanium surface introduced.
Coated with titanium powder particles in the form of titanium hydride.
Roughness depth profile of about 15µm.
6 – 10 times increase surface area. Steinmann 1988, Tetsch 1991.
68

69. Hydroxy apatite coatings :
HA coated implant bioactive surface structure shows more rapid
osseous healing when compared with smooth surface implant.
Can be indicated in:
Greater bone to implant contact area
Type IV bone
Fresh extraction sites.
Newly grafted site
Sand blasting Acid etch:
The objective of sand blasting is to increase the surface roughness
(subtractive method). The purpose of acid etching is to clean the surface from
impurities. Wennerberg et al 1996 reported superior bone fixation & bone
adaptation.
Lima YG et al (2000), Orsini z et al (2000) reported that acid etching with
NaoH, Aq. Nitric acid, hydrofluoric acid shows a decrease in contact angle by
100, further causes better cell attachment. Acid etching with 1% HF & 30%
NO3 after sand blasting shows an increase in osseointegration by removal of
aluminum particles (cleaning).
Laser induced surface roughening:
Eximer laser is used to cerate roughness.
Regularly oriented surface roughness configuration compared to TPS
coating & sandblasting
69

70. LASER INDUCED SURFACE ROUGHENING
SEM x 70
SEM x 300
SEM x 300
70

71. Physical characteristic:
Physical characteristic refers to the factors such as surface energy &
charge
Hypothesis: A surface with high energy has high affinity for adsorption which
further shows stronger osseointegration.
Baier RE (1986) reported that Glow discharge (plasma cleaning)
results in high surface energy as well as the implant sterilization, being
conductive to tissue integration.
Charge affects the hydrophilic and hydrophobic characteristic of the
surface.
A hydrophilic / easily wettable implant surface: Increases a initial phase
of wound healing.
Fact: Increase surface energy would disappear immediately after
implant placement.
Implant surface chemistry:
Chemical alteration increases bioactivity which further increase implant
bone anchorage.
71

72. Chemical surfaces:
Eg: 1. Ceramic coated - hydroxyapatite (HA), calcium phosphate.
2.
Oxidized
/
anodized
surfaces
with
electrolytes
containing
phosphorous, sulfur, calcium, magnesium and fluoride
3. Alkali and heat treatment.
4. Ionization, implantation of calcium ion, fluoride ions.
5. Doped surfaces with the bone stimulating factors / growth factors.
Anchorage mechanism or bonding mechanism in osseointegration
implants:
Biomechanical Bonding :
BIOMECHANICAL BONDING
In growth of bone into small surface irregularities of implant surface
leads to 3dimensional stabilization
72

73. Seen in:
Machined / turned screw implant
Blasted / Acid etch surface i.e., moderately rough implant surface
Based on:
Design characteristic - macrostructure (threads, vent, and slots).
Surface characteristic - microstructure (chemical surface treatment)
Biochemical bonding:
BIOCHEMICAL BONDING
Seen with certain bioactive implant surfaces like:
Calcium phosphate coated implant surfaces.
HA coated implant surfaces.
Oxidized anodized surfaces.
73

74. Bone bonding / Bonding Osteogenesis.
Bio integration
“Strong chemical bond may develop between the host bone and
bioactive implant surface and such implants are said to be biointegrated”.
Doped surfaces
DOPED SURFACES
Doped surface that contain various types of bone growth factors or
other bone stimulating agents may prove advantageous in compromised bone
beds. However, at present clinical documentation of the efficacy of such
surfaces is lacking.
LIKHOM & ZARB Classification 1985.
Class I: jaw consist almost exclusively of homogeneous compact bone.
Class II: Thick compact bone surrounds highly trabecular core
74

75. Class III: Thin cortical bone surrounds highly trabecular core
Class IV: Thin cortical bone surrounds loose, spongy core.
Osteo promotion:
Procedure to enhance the formation of bone approximating the implant
surface using bone regeneration techniques (using PTFE membrane).
Bone growth factors like PDGF, IGF, PRP, TGF – B1 stimulates
osteoprogenitar cells, enhance the bone growth.
Stefini CM et al (2000) recommend to apply PDGF and IGF on the
implant surfaces before placing in to cervical bed. This method showed better
wound healing and rapid osseointegration.
Indications:
1. Localized ridge augmentation prior to placement.
2. Treatment of peri implant bone defect.
75

76. Implantation bed / host bed:
If available, the ideal host bed is healthy and with an adequate bone
stock. However, in the clinical reality, the host bed may have suffered from
previous irradiation, ridge height resorption and osteoporosis, to mention
some undesirable states for implantation. Previous irradiation need not be an
absolute contraindication for the insertion of oral implants.
However, it is
preferable that some delay is allowed before an implant is inserted into a
previously irradiated bed. Furthermore, some 10-15% poorer clinical results
must be anticipated after a therapeutical dose of irradiation because of
vascular damage, at least in part.
One attempt to increase the healing
conditions in a previously irradiated bed is by using hyperbaric oxygen, as a
low oxygen tension definitely has negative effects on tissue repair. This is
further verified by the finding that heavy smoking, causing among other things
a local oral vasoconstriction, is one factor that will lower the expected
outcome of an implantation procedure.
Other common clinical host bed problems involve osteoporosis and
resorbed alveolar ridges. Such clinical states may constitute an indication for
ridge augmentation with bone grafts.
In jaws with insufficient bone volume for implant installation, a
grafting technique has been recommended in order to increase the amount of
hard tissues. To create more alveolar bone without grafting, a new surgical
technique was tested, relying on the biologic principle of guided tissue
76

77. regeneration. It is of great value in situations with insufficient alveolar bone
volume.
Hyperbaric oxygen therapy (HBO):
HBO elevates the partial pressure of 02 in the tissues. Granstrom G (1998)
reported that HBO can counteract some of the negative effect from irradiation
and act as a stimulator for osseointegration.
Role of HBO in Osseo integration:
Bone cell metabolism
Bone turnover
Implant interface and the capillary network in the implant bed
(angiogenesis)
Surgical Considerations:
If too violent a surgical technique is used, frictional heat will
cause a temperature rise in the bone and the cells that should be responsible
for bone repair will be destroyed. Bone tissue is more sensitive to heat than
previously believed. No implant becomes tissue-integrated at the time of its
insertion in the body, as bone and soft tissue cannot be surgically prepared
without production of heat and subsequent superficial tissue death in the
implant bed. This necrotic bone must be replaced with new, living hard tissue
to achieve implant osseointegration, which is defined as living, active bone in
direct contact with the loaded implant surface. If a non optimized surgical
77

78. technique is used, severe, heat production is inevitable; this results in wide
zones of bone necrosis that are too wide to allow for bone healing. Instead,
fibrous tissue formation replaces bone, and there is a primary failure of
osseointegration that will not be compensated for later. Once new fibrous
tissue has been established in the interface, it remains there without further
differentiation to bone or any other structure of a higher order.
In the past the critical temperature was regarded to be in the 56 0C
range, as this temperature will cause denaturation of one of the bone
enzymes, alkaline phosphatase.
However, the critical time/temperature
relationship for bone tissue necrosis is around 470C applied for one minute.
At a temperature of 500C applied for more than one minute we are coming
close to a critical level where bone repair becomes severely and permanently
disturbed. High drilling temperatures in the dental field are to be expected
when drilling, particularly in the dense mandible using well sharpened drills,
slow drill speeds, a graded series of drills (avoid making, for instance, a 4 mm
hole in one step) and adequate cooling. By using such a controlled technique
it has been demonstrated in clinical studies that overheating may be totally
avoided. The mechanical injury will of course remain and is quite sufficient to
trigger a proper healing response.
During this healing time, the anchorage of the implant is not optimal,
and there is a delicate balance between bone resorption and formation
necessary to establish a reliable bone anchorage.
78

79. Another surgical parameter of relevance is the power used at implant
insertion.
Too strong a hand will result in bone tension and a resorption
response will be stimulated. This means that the holding power of the implant
will fall to dangerous levels after a strong insertion torque. A moderate power
at the screwing home of an implant is therefore recommended. With other
implant designs there may be a need for impaction of the implant at insertion
and other rules may apply.
Implant Loading:
Irrespective of control of surgical trauma and other relevant
parameters, the implant will, in the early remodelling phase, be surrounded by
soft tissue. This means that some weeks after implant insertion it will be
particularly sensitive to loading that results in movements, as movement will
stimulate more soft-tissue formation, leading eventually to a permanent softtissue anchorage. In essence, the situation is similar to that of a fracture.
The case of an implant is, in principle, very similar. Premature loading will
lead to soft-tissue anchorage and poor long-term function, whereas
postponing the loading by using a two-stage surgery will result in bone healing
and positive long-term function. The length of time that the loading should be
avoided is dependent on the implantation site well as on the bone bed quality.
Branemark with his controlled implant system advocated the use of a 3-month
delay in the healthy maxilla where the bone is, as a rule, more cancellous in
character.
79

80. Premature loading leads to
implant movement
The end result “Soft
tissue interface”
“Bony interface”
80

81. Different philosophies regarding loading conditions:
Branemark Albrektsson reported a two stage implant insertion technique.
First stage
Installation of fixture in to bone
Second stage
Connection of abutment to the fixtures
Misch reported Progressive / Gradual loading.
Suggested in
Softer bone.
Where less number of implants to be used.
Immediate function loading protocol:
Clinical trials showed successful osseointegration (95 – 100% success
rate – completely edentulous patients) when bone quality is good and
functional forces are controlled. More favorable in mandible compared to
maxilla.
Over
loading
causes
stress
concentration,
undermining
bone
resorption with out apposition (Branemark 1984).
To decrease the bio – mechanical load:
. Prosthetic design considerations.
. Cantilever length may be shortened or eliminated.
. Narrow occlusal table.
. Minimizing the offset load.
. Increasing the implant number.
. Use of wider implant with D4 bone compared to D1 & D2.
81

82. Bone – metal Interface in osseointegration:
Clinical Approaches To Describe The Osseointegrated Interface:
Many
methods
have
been
tried
to
clinically
demonstrate
osseointegration of an implanted alloplastic material. These tests have been
used to indicate, not to verify, osseointegration, which is a concept defined at
the histological level. These are:5,34
1. Performing a clinical mobility test, and finding that the implant is mobile
is definite evidence that it is nonintegrated. The presence of clinical
stability cannot be taken as conclusive evidence of osseointegration.
Radiological level
Macroscopic level
Histological level
82

83. Radiographs demonstrating a seemingly direct contact between bone
and implant have been cited as evidence of osseointegration.
Radiolucent zones around the implant are a clear indication of its being
anchored in fibrous tissue, where as the lack of such zone is not
evidence for osseointegration. The reason for this is that the optimal
resolution capacity of radiography is in the range of 0.1.mm where as
the size of a soft tissue cell is in the range of 0.01 mm; thus a narrow
zone of fibrous tissue may be undetectable by radiography.
2. The use of a metal instrument to tap the implant and analyze the
transmitted sound may, in theory, be used to indicate a proper
osseointegration. However, there is no typical “sound diagram” defined
for the osseointegrated implant in contrast to the implant anchored in
fibrous tissue.
Therefore, clinical tests of implant interfacial arrangements are only capable
of roughly indicating the true tissue responses.
Experimental Evidence Of The Bone – To - Metal Interface:
Albrektsson summarized various opinions on the bone–to-titanium
interface and concluded that many authors described soft tissue anchorage of
titanium bone implants because of a failure to realize
the multifarious
problems associated with implantation of a foreign conditions, surgical
technique, and loading conditions are properly controlled, osseointegration of
83

84. a titanium implant is a predictable response and, once achieved, the direct
bone anchorage will remain over periods of decades or more, provided
unphysiologic loads are not applied.68,82
Histologic examination provides the best evidence of the type of
implant attachment. The resolution power is sufficient to characterize the
interface of intervening soft tissue cells and the magnification reveals the
overall tissue response. A properly osseointegrated implant at the cortical
passage should have a minimal direct bone contact of 90% to 95% of the
implant surface. This high degree of osseointegration should completely
surround the circumference of a cylindrical implant.34,40
As summarized by Albrektsson, collagen bundles become gradually
replaced by randomly arranged filaments at a distance of 0.1 to 0.5 µm from
the titanium. The collagen filaments reached as close as about 200 A 0 from
the implant surface. There is partly calcified amorphous ground substance
consisting of proteoglycans and glucoseaminoglycans covering the last 200 to
300 A0 of the interface toward the metal. No decalcified space is found
between the titanium and tissue, but the calcification was less pronounced in
the last few hundred A0 from the titanium surface. Cell processes that
approached the titanium surface were like wise separated from it by a 200 to
300 A0 thick proteoglycan layer.5,34
84

85. Although metals such as zirconium demonstrate osseointegration, the
collagen free zone is slightly thicker than the titanium interface, which indicate
that zirconium is less “nature - like” than titanium. Other materials such as
stainless steel do not become properly osseointegrated, but are separated
from the tissue by a thin cellular coat.
Osseointegration from the perspective of inter molecular forces:
According to Albrektsson et al.6,7 Calcified tissue reaches within 50 A0
of the implant surface. The metal surface is in fact a highly polarizable
titanium oxide layer probably modified by accumulated impurities from the
bulk metal phase. Specific treatment prior to implantation is critical to
successful tissue incorporation. With time the titanium oxide surface blends
with material from adjacent tissue, and a thin layer of ground substance of
cellular origin is deposited on the implant so as to “cement” bone tissue and
titanium. The interactions of principal importance are electrostatic rather than
Van Der Waals or “hydrophobic” interactions. To a charged body the highly
polar oxide layer provides a strongly attractive alternative to water. The many
configurations of titanium and oxygen likely to occur in such a surface provide
a wide variety of adsorbent sites to attract various arrays of charges that
probably reside on the water – soluble ground substance. V. Adrian Parsegian
even expected spots of strong contact involving charge constellations such as
those seen among dimerizing proteins.68
85

86. He was struck first by the fact that the oxide layer is so highly polar and
therefore able to attract species that are ordinarily water soluble. Positive
electric charges in particular will move toward the oxide, for in addition to its
polarizability the layer is negatively charged. It should not be surprising that
such a highly polar region has been observed to incorporate (positive) calcium
and (negative) phosphate ions from the adjacent aqueous phase. 5
Ion adsorption to surfaces also introduces the likelihood of ionic
bridges to larger adsorbents. Close apposition has repeatedly been observed
for cases where calcium can fit between two negative surfaces. It is entirety
likely that negatively charged cellular exudates could be similarly attached to
metallic oxide surface. The particular configuration of oxygen and titanium
provides a mosaic for match up with the cementing ground substance. 5,34
BIOMECHANICAL CONSIDERATIONS:
Stress Transfer From Implants To Bone
A critical aspect affecting the success or failure of an implant is the
manner in which mechanical stresses are transferred from the implant to
bone. It is essential that neither implant nor bone be stressed beyond the long
– term fatigue capacity. It is also necessary to avoid any relative motion that
can produce abrasion of the bone or progressive loosening of the implant.
These requirements are met by osseointegrated implants by virtue of the
close apposition of the bone to the implant at the angstrom level.82
86